Of the many techniques for brewing coffee, connoisseurs consider the French press technique to be one of the best for taste and efficient use of ground coffee (efficiency is proportional to the ratio of the amount of coffee brewed to the amount of ground coffee used). It is theorized that the good taste and efficiency is a result of the relatively thorough wetting of the coffee grounds that the French press technique allows. Wetting is a function of the surface area of the coffee grounds in contact with water during the brewing time, and of the portion of the brewing time during which this contact occurs. The greater the contact area and contact time, the more thorough the wetting of the coffee grounds.
Referring to FIGS. 1 and 2, the French press technique is described.
Referring to FIG. 1, one places ground coffee 10 and hot water 12 in a coffee container 14, and allows coffee to brew. Because the ground coffee 10 often floats to the surface of the water 12, one may stir or otherwise agitate the mixture of the ground coffee and the water to more thoroughly wet the individual coffee grounds that constitute the ground coffee.
Referring to FIG. 2, after the coffee 15 has brewed, one grasps a handle 16 of a filter 18, inserts the filter into the coffee container 14, and presses the filter down toward the bottom of the pot. For the taste of the brewed coffee to be relatively uniform from container to container, one typically uses and manually monitors a timer to measure the brew time.
Because the filter 18 passes liquid but does not pass coffee-ground-sized particles, as one presses the filter toward the bottom of the coffee container 14, the substantially ground-free brewed coffee 15 fills the portion of the container above the filter while the filter retains the ground coffee 10 in the portion of the container below the filter. Of course the edge 20 of the filter 18 and the inner side 22 of the container 14 form a seal sufficient to prevent coffee grounds from passing between the edge of the filter and the inner side of the container.
After one presses the filter 18 below a spout 24 of the coffee container 14, he can pour the substantially ground-free brewed coffee 15 into a cup (not shown in FIGS. 1 and 2) via the spout. Although one may stop pressing the filter 18 after the filter is below the spout 24, one typically presses the filter all the way to the bottom of the coffee container 14 to reduce the chances of undersized coffee grounds passing through the filter and into the cup.
Still referring to FIG. 2, after one pours the desired amount of brewed coffee 15, he retracts the filter 18 from the container 14 by pulling on the handle 16, removes the ground coffee 10 from the container, and then cleans the filter and the container.
Unfortunately, a problem with the above-described French press technique is that it is often too time consuming and too difficult for use by establishments, such as coffee shops, restaurants, and work places that serve significant amounts of coffee. The taste of brewed coffee typically depends on the brew parameters, which include the size of the coffee grounds (i.e., the grind size or consistency), the water temperature, the ratio of ground coffee to water, and the brew time. Even a slight variation in one of the brew parameters may cause a noticeable change in the taste of the brewed coffee. Because one typically controls at least some of the French press brewing parameters manually using equipment not shown in FIGS. 1-2 (e.g., coffee grinder, timer, thermometer, measuring cup), it is often difficult or time consuming to control all of these brewing parameters, particularly with the level of precision required to brew many containers of coffee having a substantially uniform taste from container to container. And because each cup of brewed coffee poured from the same container typically “sat” in the container for a different length of time, the taste of the brewed coffee may even change significantly from cup to cup.